1. Field of the Invention
The present invention relates to vessel filters and vessel delivery systems. More particularly, the present invention relates to an improved vessel filter and delivery system having a delivery catheter of improved configuration that accepts a filter in a folded condition wherein the filter has specially configured appendages with outwardly directed hooks that engage indentations or recesses in the catheter wall.
2. General Background of the Invention
A vessel filter is a device inserted into a blood vessel to capture particles in the blood flow. Typically the device is inserted into a major vein to prevent a blood clot from reaching the lungs. Patients, who have recently suffered from trauma, have experienced a heart attack (myocardial infarction), or who have undergone major surgical procedure (e.g., surgical repair of a fractured hip, etc.) may have thrombosis in a deep vein. When the thrombus clot loosens from the site of formation and travels to the lung it may cause pulmonary embolism, a life-threatening condition. A vessel filter may be placed in the circulatory system to intercept the thrombi and prevent them from entering the lungs.
Examples of various blood vessel filters and delivery systems are disclosed in the following table:
TABLEPAT. NO.TITLEISSUE DATE2001/0000799 A1“BODY VESSEL FILTER”May 3, 20012002/0038097 A1“ATRAUMATIC ANCHORING ANDSep. 26, 2002DISENGAGEMENT MECHANISM FORPERMANENT IMPLANT DEVICE”2002/0193828 A1“ENDOVASCULAR FILTER”Dec. 19, 20022003/0199918 A1“CONVERTIBLE BLOOD CLOT FILTER”Oct. 23, 20032003/0208227 A1“TEMPORARY VASCULAR FILTERSNov. 6, 2003AND METHODS”2003/0208253 A1“BLOOD CLOT FILTER”Nov. 6, 20032004/0082966 A1“STAGED RELEASE OF IVC FILTER LEGSApr. 29, 20044,425,908“BLOOD CLOT FILTER”Jan. 17, 1984;4,643,184“EMBOLUS TRAP”Feb. 17, 1987;4,817,600“IMPLANTABLE FILTER”Apr. 4, 1989;5,059,205“PERCUTANEOUS ANTI-MIGRATIONOct. 22, 1991;VENA CAVA FILTER”5,147,379“INSERTION INSTRUMENT FORSep. 15, 1992;VENA CAVA FILTER”5,626,605“THROMBOSIS FILTER”May 6, 1997;5,634,942“ASSEMBLY COMPRISING A BLOODJun. 3, 1997;FILTER FOR TEMPORARY ORDEFINITIVE USE AND A DEVICEFOR IMPLANTING IT”5,755,790“INTRALUMINAL MEDICAL DEVICE”May 26, 1998;5,853,420“ASSEMBLY COMPRISING A BLOODDec. 29, 1998;FILTER FOR TEMPORARY ORDEFINITIVE USE AND A DEVICEFOR IMPLANTING IT, CORRESPONDINGFILTER AND METHOD OF IMPLANTING SUCHA FILTER”6,258,026 B1“REMOVABLE EMBOLUS BLOOD CLOTJul. 10, 2001;FILTER AND FILTER DELIVERY UNIT”6,342,062 B1“RETRIEVAL DEVICES FOR VENAJan. 29, 2002;CAVA FILTER”6,383,193 B1“VENA CAVA DELIVERY SYSTEM”May 7, 2002;6,497,709 B1“METAL MEDICAL DEVICE”Dec. 24, 2002;6,506,205 B2“BLOOD CLOT FILTERING SYSTEMJan. 14, 2003;6,517,559 B1“BLOOD FILTER AND METHOD FORFeb. 11, 2003;TREATING VASCULAR DISEASE”6,540,767 B1“RECOILABLE THROMBOSISApr. 1, 2003;FILTERING DEVICE AND METHOD”6,620,183 B2“THROMBUS FILTER WITH BREAK-Sep. 16, 2003;AWAY ANCHOR MEMBERS”Each of above listed patents is incorporated herein by reference in its entirety.
Typically, the filter comprises a plurality of radially expandable legs that support one or more filter baskets having a conical configuration. The device is configured for compression into a small size to facilitate delivery into a vascular passageway and is subsequently expandable into contact with the inner wall of the vessel. The device may later be retrieved from the deployed site by compressing the radially expanded legs and the associated baskets back into a small size for retrieval. The radially expandable leg may further comprise engagements for anchoring the filter in position within a blood vessel (e.g., vena cava). For example, the expandable legs may have hooks that can penetrate into the vessel wall and positively prevent migration of the filter in either direction along the length of the vessel. The body of the filter may comprise various biocompatible materials including compressible spring metals and shape memory materials to allow easy expansion and compression of the filter within the vessel. The hooks on the radially expandable legs may further comprise materials more elastic than the legs to permit the hooks to straighten in response to withdrawal forces to facilitate withdrawal from the endothelium layer without risk of significant injury to the vessel wall. The hooks may be formed on selected radially expandable legs, but not on others.
Many of the existing vena cava filters routinely encounter problems during deployment due to entanglements of the radially expandable legs. This is especially problematic in designs with hooks implemented on the radially expandable legs. In the compressed/collapsed condition, the various hooks on the legs may interlock with other legs or hooks and render the device useless. Thus, an improved vessel filter delivery device that can prevent entanglement and/or interlocking of the radially expandable legs when the filter is collapsed and placed inside the delivery device is desirable.